Quantitative human behavioural genetics is a specialisation in the
biologicalBiology is the natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy...
field of behaviour genetics that studies the role of
geneticsGenetics, , a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding...
in
humanHumans are bipedal primates belonging to the species Homo sapiens in Hominidae, the great ape family. They are the only surviving member of the genus Homo. Humans have a highly developed brain, capable of abstract reasoning, language, introspection, and problem solving...
behaviour employing
quantitative-geneticQuantitative genetics is the study of continuous traits and its underlying mechanisms. It is effectively an extension of simple Mendelian inheritance in that the combined effect of the many underlying genes results in a continuous distribution of phenotypic values.- History :The field was...
methods. The field is an overlap of quantitative genetics and
psychologyPsychology is an academic and applied discipline involving the systematic, and sometimes scientific, study of human or animal mental functions and behavior...
. Classically, human behavioural geneticists have studied the inheritance of behavioural traits.
History
In 1869,
Francis GaltonSir Francis Galton FRS , cousin of Sir Douglas Galton, was an English Victorian polymath, anthropologist, eugenicist, tropical explorer, geographer, inventor, meteorologist, proto-geneticist, psychometrician, and statistician. He was knighted in 1909.Galton had a prolific intellect, and produced...
published the first empirical work in human behavioural genetics,
Hereditary Genius. Here, Galton intended to demonstrate that "a man's natural abilities are derived by inheritance, under exactly the same limitations as are the form and physical features of the whole organic world." Like most seminal work, he overstated his conclusions. His was a family study on the
inheritance of giftedness and talentStudy of the heritability of IQ is a controversial field of research that includes biology, psychology, philosophy, sociology, and anthropology. Heritability is a measure of the relative contribution of genotype to the variation of a phenotype on a given group in a specific environment...
. Galton was aware that resemblance among familial relatives can be a function of both shared inheritance and shared environments. Contemporary human behavioural quantitative genetics studies special populations such as
twinsTwin studies are one of a family of designs in behavior genetics which aid the study of individual differences by highlighting the role of environmental and genetic causes on behavior....
and
adopteesAdoption is a process whereby a person assumes the parenting for another who is not kin and, in so doing, permanently transfers all rights and responsibilities from the original parent or parents...
.
The initial impetus behind this research was to demonstrate that there were indeed genetic influences on human behaviour. In psychology, this phase lasted for the first half of the 20th century largely because of the overwhelming influence of behaviourism in the field. Later behavioural genetic research focused on quantitative methods.
Contemporary behavioural quantitative genetics
Currently, the largest branch of human behavioural genetics is
psychiatric geneticsPsychiatric genetics, a subfield of behavioral neurogenetics, studies the role of genetics in psychological conditions such as alcoholism, schizophrenia, bipolar disorder, and autism. The basic principle behind psychiatric genetics is that genetic polymorphisms, as indicated by linkage to e.g...
which studies phenotypes such as
schizophreniaSchizophrenia , from the Greek roots skhizein and phrēn, phren- is a psychiatric diagnosis that describes a mental disorder characterized by abnormalities in the perception or expression of reality...
,
bipolar disorderBipolar disorder, also known as manic depressive disorder, manic depression or bipolar affective disorder, is a serious mental disorder that describes a category of mood disorders defined by the presence of one or more episodes of abnormally elevated mood clinically referred to as mania or, if...
, and
alcoholismAlcoholism is a term with multiple and sometimes conflicting definitions. In common and historic usage, alcoholism is any condition that results in the continued consumption of alcoholic beverages, despite health problems and negative social consequences...
.
Recent trends in behaviour genetics have indicated an additional focus toward researching the inheritance of human characteristics typically studied in
developmental psychologyDevelopmental psychology, also known as human development, is the scientific study of systematic psychological changes that occur in human beings over the course of the life span. Originally concerned with infants and children, the field has expanded to include adolescence and adult development,...
. For instance, a major focus in developmental psychology has been to characterize the influence of parenting styles on children. However, in most studies, genes are a confounding variable. Because children share half of their alleles with each parent, any observed effects of
parenting stylesParenting style is a psychological construct representing standard strategies parents use in raising their children.- Four general parenting styles :One of the best known theories of parenting style was developed by Diana Baumrind...
could be effects of having many of the same alleles as a parent (e.g. harsh aggressive parenting styles have been found to correlate with similar aggressive child characteristics: is it the parenting or the genes?). Thus, behaviour genetics research is currently undertaking to distinguish the effects of the family environment from the effects of genes. This branch of behaviour genetics research is becoming more closely associated with mainstream
developmental psychologyDevelopmental psychology, also known as human development, is the scientific study of systematic psychological changes that occur in human beings over the course of the life span. Originally concerned with infants and children, the field has expanded to include adolescence and adult development,...
and the sub-field of
developmental psychopathologyDevelopmental psychopathology is the study of the development of psychological disorders, such as psychopathy, autism, schizophrenia and depression, with a lifecourse perspective....
as it shifts its focus to the heritability of such factors as emotional
self-controlSelf control is the ability to control one's emotions and desires, is the capacity of efficient management to the future.In psychology it is sometimes called self-regulation, and exerting self-control through the executive functions in decision making is thought to deplete a resource in the...
, attachment, social functioning, aggressiveness, etc.
Several academic bodies exist to support behaviour genetic research, including the
International Behavioural and Neural Genetics SocietyThe International Behavioural and Neural Genetics Society was founded in 1996. The goal of IBANGS is "to promote the field of neurobehavioural genetics".- Mission :...
,
Behavior Genetics AssociationThe Behavior Genetics Association promotes research into the connection between heredity and behavior. Its science journal is titled Behavior Genetics, "the leading journal concerned with the genetic analysis of complex traits."...
, the International Society for Psychiatric Genetics, and the International Society for Twin Studies. Behaviour genetic work features prominently in several more general societies, for instance the
International Behavioral Neuroscience SocietyThe International Behavioral Neuroscience Society , was founded in 1992. The goal of the IBNS is to "encourage research and education in the field of behavioral neuroscience". Its current president is Robert T. Gerlai...
.
Methods of human behavioural genetics
Human behavioural geneticists use several designs to answer questions about the nature and mechanisms of genetic influences on behaviour. All of these designs are unified by being based around
human relationshipsAn interpersonal relationship is an association between two or more people that may range from fleeting to enduring. This association may be based on limerence, love and liking, regular business interactions, or some other type of social commitment...
which disentangle genetic and environmental relatedness.
So, for instance, some researchers study adopted twins: the adoption study. In this case the adoption disentangles the genetic relatedness of the twins (either 50% or 100%) from their family environments. Likewise the classic
twin studyTwin studies are one of a family of designs in behavior genetics which aid the study of individual differences by highlighting the role of environmental and genetic causes on behavior....
contrasts the differences between
identical twinsTwins are two offspring resulting from the same pregnancy, usually born in close succession. They can be the same or different sex. Twins can either be monozygotic or dizygotic ....
and fraternal twins within a family compared to differences observed between families. This core design can be extended: the so-called "extended twin study" which adds additional family members, increasing power and allowing new genetic and environmental relationships to be studied. Excellent examples of this model are the Virginia 20,000 and the QIMR twin studies.
Also possible are the "children of twins" design (holding maternal genetic contributions equal across children with paternal genetics and family environments; and the "virtual twins" design - unrelated children adopted into a family who are very close or identical in age to biological children or other adopted children in the family. While the classical
twin studyTwin studies are one of a family of designs in behavior genetics which aid the study of individual differences by highlighting the role of environmental and genetic causes on behavior....
has been criticized they continue to be of
high utility. There are several dozen major studies ongoing, in countries as diverse as the USA, UK, Germany, France,
The NetherlandsThe Netherlands is a country in Northwestern Europe, constituting the major portion of the Kingdom of the Netherlands. It is a parliamentary democratic constitutional monarchy. The Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east...
, and Australia, and the method is used widely in fields as diverse as
dental cariesDental caries, also known as tooth decay or cavity, is a disease wherein bacterial processes damage hard tooth structure . These tissues progressively break down, producing dental cavities . Two groups of bacteria are responsible for initiating caries: Streptococcus mutans and Lactobacilli...
,
BMIThe body mass index , or Quetelet index, is a controversial statistical measurement which compares a person's weight and height. Though it does not actually measure the percentage of body fat, it may be a useful tool to estimate a healthy body weight based on how tall a person is...
, aging,
substance abuseAlthough the term substance can refer to any physical matter, substance abuse has come to refer to the overindulgence in and dependence of a drug or other chemical leading to effects that are detrimental to the individual's physical and mental health, or the welfare of others.]The disorder is...
,
sexualityHuman sexuality is how people experience the erotic and express themselves as sexual beings. Frequently driven by the desire for sexual pleasure, human sexuality has biological, physical and emotional aspects...
,
cognitive abilitiesIntelligence is an umbrella term used to describe a property of the mind that encompasses many related abilities, such as the capacities to reason, to plan, to solve problems, to think abstractly, to comprehend ideas, to use language, and to learn. There are several ways to define intelligence...
,
personalityPersonality may refer to:*Personality psychology is the theory and study of personality types, personality traits and individual differences*Personality development, the study of personality development over time...
, values, and a wide range of psychiatry disorders. This is broad utility is reflected in
several thousands of peer-review papers, and several dedicated societies and journals (See
Twin studyTwin studies are one of a family of designs in behavior genetics which aid the study of individual differences by highlighting the role of environmental and genetic causes on behavior....
).
External links